The general assembly of stringed instruments is well known in the art. For example in a piano type arrangement, a plurality of strings are tensioned across a string attachment structure, such as a plate, so that each string may vibrate when struck by a hammer. The strings define the frequency of the note and convert some of the kinetic energy of the moving hammer into vibrational energy with components of vibration in planes parallel and perpendicular to the plate. Piano strings are typically arranged either horizontally (as in a grand piano) or vertically (as in an upright piano) and are generally subdivided into three major groupings: bass, low treble and high treble. Bass commonly refers to the lower-pitched notes, while treble refers to the higher pitched notes. In a piano type arrangement, there are typically three strings for each high treble note, two strings for each low treble note, and one string for each bass note. Each set of one, two, or three strings is often referred to as a unison. There is typically provided one key for each unison or note. A piano generally has 88 keys, and hence 88 notes, spanning at least the frequency range from the note A0 at 27.5 hz to the note C8 at 4186 hz.
In a piano type arrangement, the strings engage a bridge structure for transferring their vibrational energy to a sound amplifying structure, or soundboard. Typically, the bridge structure is disposed transverse to the strings and comprises two angled bridge pins for each string (although some musical instruments, such as a harpsichord, typically are provided with only one bridge pin), with both pins being attached to a curved rib having a top face. Each string has a bearing point, sometimes referred to as a speaking, or vibrating length terminus, located at the bridge structure. Both pins were typically specified to be installed at an angle so that the strings are down-bearing against the bridge and side-bearing against the pins. Such angled bridge pins were believed to be necessary to avoid undesirable performance characteristics, such as strings moving off their designated bearing point at the bridge structure when excited. In fact, inadvertent installation of pins having insufficient angle was to be avoided, as it could similarly cause such performance problems.
The down and side bearing relationship of the strings with the bridge structure also aids in transmitting their vibrational energy to the bridge structure and, in part, defines the mechanical coupling therebetween. Because the strings are the principal reservoir for storing vibrational energy, it is known in the art that the magnitude and manner of the excitation and the boundary conditions of the string are important for determining the tone of a string, although the reasons and interaction are often not fully understood. For example in a piano, the string is typically excited by the impact of a hammer having an impact velocity, the velocity being dependent upon the force input of the pianist at the piano key. It is contemplated that the impact velocity, the physical hardness and density characteristics of the hammer (and its felt covering), and the method of coupling the string to the bridge structure defines, in part, the initial tone of the string.
The tone of a string is often defined by the harmonic content and decay time of the string. When a string is excited (such as by striking with a hammer), it will vibrate at a fundamental frequency which is determined by the vibrating or speaking length of the string, the tension of the string, and the mass per unit length of the string. The string will also vibrate at integer multiples of the fundamental frequency, often referred to as overtones, as well as frequencies producing a "glassy" sound which do not contribute to the perceived pitch of the note. The relative strength, or amplitude, of the fundamental frequency, the overtones, and the frequencies producing the glassy sounds, often together referred to as a spectrum, define the string's harmonic content. The larger the amplitude of the fundamental frequency and the lower overtones (e.g., generally the first 5 to 10 integer multiples of the fundamental frequency depending on whether the string is generally in the high treble, low treble, or bass range), the clearer and more desirable the tone; while alternatively, the more frequencies producing glassy sounds and the greater their amplitudes, the less desirable the tone.
In addition to the harmonic content of a string, the decay rate of the additive amplitude of the string's excited frequencies (e.g., the fundamental frequency, the overtones, and other associated frequencies) is also important in determining a string's tonal quality. In general, the longer the decay time the more desirable the tone. It is even more desirable that the decay time be fairly uniform from note to note so that the multiple notes blend in pleasing harmony with each other when played together. For example, in typical piano type arrangements it is sometimes difficult to achieve a good balance that enables the 5th octave and above of the keyboard (notes C5 through F6, often referred to as the melody range) to sustain long enough (i.e., having a long enough decay time) against the inherently longer decay time of the lower octave ranges (notes C1 through C5).
While previously available bridge structures may function well for the purposes for which they were designed, it has often been desirable, and continues to be desired, to provide improved bridge structures with additional operational advantages. For example, it would be desirable to provide a string arrangement which increases a string's decay time so that juxtaposed notes from different ranges in the piano sound well together. It would also be advantageous to provide an improved string arrangement and bridge structure which reduces the glassy sounds associated with a note and which also produces a clearer note. The present invention provides such an improved string arrangement which can accommodate designs having the abovedescribed tonal benefits and features.